Calls build() each time I call ref.read method

[dyardy]

I have the following Provider, which maintains the user position (lat and long). Within my user interface, this is called when the position changes.

ref.read(positionNotifierProvider.notifier).updateLocation(MyWeatherPosition(position.latitude, position.longitude));

The problem is every time this updateLocation is called, the build() is called, setting the state back to its original position. I expected this would only be called once if the user stayed on that page.

  @override
  MyWeatherPosition build() {
    return MyWeatherPosition(39.327787, -84.379258);
  }

As a work-around used @Riverpod(keepAlive: true) (which ensures that build is only called once) but this is not preferred.

Am I doing something incorrect?

@riverpod
class PositionNotifier extends _$PositionNotifier {
  
  @override
  MyWeatherPosition build() {
    return MyWeatherPosition(39.327787, -84.379258);
  }

  void updateLocation(MyWeatherPosition positionItem) {
    if (isDifferent(positionItem)) {
      state = positionItem;
       ref.read(positionItemClassProvider.notifier).Add(positionItem);
    }
  }

  bool isDifferent(MyWeatherPosition newPosition) {
    if (state.lat != newPosition.lat || state.lon != newPosition.lon) {
      return true;
    }

    return false;
  }
}

and within my ConsumerState class

void _updatePositionList(PositionItemType type, String displayValue, Position? position) {
    if (position != null) {
      ref
          .read(positionNotifierProvider.notifier)
          .updateLocation(MyWeatherPosition(position.latitude, position.longitude));      
    }
  }

[dyardy]

As a check I used the old approach and didn't have any trouble.

I thought my @riverpod annotation was equivalent to this below.

For completeness, I used this to call the update

   ref
          .read(positionNotifier2Provider.notifier)
          .updateLocation(MyWeatherPosition(position.latitude, position.longitude));

class PositionNotifier2 extends StateNotifier<MyWeatherPosition> {
  PositionNotifier2(this.ref) : super(MyWeatherPosition(39.327787, -84.379258));

  Ref ref;

  void updateLocation(MyWeatherPosition positionItem) {
    if (isDifferent(positionItem)) {
      state = positionItem;
      ref.read(positionItemClassProvider.notifier).Add(positionItem);
    }
  }

  bool isDifferent(MyWeatherPosition newPosition) {
    if (state.lat != newPosition.lat || state.lon != newPosition.lon) {
      return true;
    }

    return false;
  }
}

final positionNotifier2Provider = StateNotifierProvider<PositionNotifier2, MyWeatherPosition>((ref) {
  return PositionNotifier2(ref);
});

[motucraft]

This is not equivalent to @riverpod because StateNotifierProvider is not StateNotifierProvider.autoDispose, right?
If you don't add .autoDispose, I think it is equivalent to @Riverpod(keepAlive: true).

[dyardy]

I found a clue which resolved the problem. By default, the provider will start up and be available on the page (without newing up again) if there is a watch on that page. Without the specific watch on the page, the provider would start fresh each time.